Pain endures. Pain will persist until the source of the pain is removed. Until the splinter is removed, until the diseased limb is cut off, until the slave wins their freedom, until you manage to buy that shiny new car that trumps your neighbour's status symbol, you will feel the stick driving you on.

After a brief dose of the reward of happiness, we begin to want something else. So we are programmed to look for the next goal. We progress up Maslow's hierarchy of needs. It is our nature never to experience enduring satisfaction. We are machines built to want and want.

Skow makes the case that the neurochemical brain is a dynamic system, and happiness, though a temporary state, is a natural one, so "imbalance" may be too strong a word for it.

Yes, those imbalances, those temporary alterations of brain chemistry can make us happy, so very joyous. Nirvana, the abolition of need not by the impossible task of satisfying all possible needs, but by temporarily short-circuiting gratification itself. True inner peace. And it leaves one low and flat afterwards, living for a few days in a world bereft of all the brightness and dimensions that we have experienced. Dull, unhappy.